The present conventional roofing techniques involve an overlapping of the roofing panels. For example, in order to minimize leakage through the joints of abutting panels in a row, a further row of panels is mounted over the underlying row in a staggered manner to cover the joints. Added overall panel thickness results by overlapping the rows of panels from the base edge of the roof upwards. The multiple thickness results in excessive weight and cost. Where sufficient measures are not taken to seal the joints, there is the tendency to permit water, such as rain, to flow through the joint of adjacent panels and directly contact the understructure. Where a wooden deck is used as the understructure, the water can cause the wooden deck to rot. Where a metal deck is used the water can cause corrosion.
A known system marketed under the name roof lock systems by GREAT SLATE PTY LTD. of Adelaide, Australia is described in Australian patent application no. 60521/94 and counterpart U.S. Pat. No. 5,642,596. The '596 patent discloses essentially two embodiments. In one embodiment illustrated in FIGS. 1-4 the joining strips 13 are mechanically interlocked with battens of generally Z-shape by having marginal flanges 15 extend below the main portion of the strip. The flanges includes slots 16 which engage an upper edge of the batten near the lower end of the strip. The strip includes a pair of tabs 20 at its lower end, each of which would be crimped over a respective shingle to hold the shingle in place. The strip is of a length so that its upper end rests against the vertical portion of the Z-shaped batten rather than on the upper surface. In a further embodiment shown in FIGS. 5-6 the upper end of the strip 13 has, in additional to marginal flanges 15, an L-shaped bracket which extends upwardly from its main surface and is mounted over the upper surface of the batten. Instead of having tabs to hold the shingles a bent locking finger is located at the upper portion of the strip to hold a single shingle.
It would be desirable to provide a roofing assembly which adopts some of the advantages of the embodiments described in the '596 patent while having its own advantages such as in ease of installation, improved appearance and compliance.